Sewer backups, where the main sewer line overflows and forces raw sewage back into a building sewer line such as that of a home, can be a significant problem. Such backups can lead to basement flooding or worse.
To guard against such backups, it is now common to interpose a backwater valve between a building sewer line and the main sewer line. Various designs have been proposed over the years, and in 1995 Gabe Coscarella and Vitto Chiodo were granted U.S. Pat. No. 5,406,972 (the teachings of which are hereby incorporated by reference) for a normally open backwater valve. The Coscarella and Chiodo valve includes a buoyant, pivoting gate disposed in the body of the valve. When sewage is flowing normally, the gate will be in a lowered position in which water can flow from the home or other building past the gate through the body of the valve toward the sewer. However, in the event of a sewer backup, the inflow of sewage causes the buoyant gate to pivot upwardly into sealing engagement with the valve inlet to prevent the sewage from entering the inlet and infiltrating the home.
It has also been proposed to incorporate sensors into a backwater valve to detect and trigger an alarm in the event of a sewer backup (see, for example, Canadian Patent Application No. 2,825,895 and U.S. Pat. No. 5,113,901).
It would be desirable, however, to detect conditions that are likely to lead to a sewer backup before such a backup actually occurs, so that corrective measures can be taken. For example, in areas where clay pipes are used in the sewer system, infiltration by tree roots can, over time, occlude a sewer pipe, and it would be desirable to detect and remedy such infiltration before the pipe is completely occluded and a sewer backup results.